First we learn what defines a living thing and that they need air, water and food. Animals in general are addressed and readers are introduced to vertebrates and invertebrates. The text becomes more specific with the introduction of arthropods which are invertebrates that have legs that bend; there is a definition of reptiles and amphibians as well as fish, birds and mammals. Some of the pages have quizzes to see if readers can correctly identify the classification of the animals. At the end readers learn that plants are also living things as well as a special category of living things called fungi.